A method and an apparatus for producing amorphous metal strips are known (e.g., European Pat. No. 0,026,812), wherein a metallic melt from a storage container is forced from at least one nozzle opening and is solidified on the surface of a cooler moved past and in the immediate vicinity of the nozzle opening. When circular nozzles with a diameter of 0.5 to 1 mm are used for producing amorphous metal strips, there is an optimum relationship between the nozzle opening, the distance between the nozzle opening and the cooler surface, and the speed of the cooler surface. This permits the production of uniformly formed metal strips at high production speeds. Such strips can either be completely amorphous or have a two-phase amorphous/crystalline mixture. The term amorphous metal alloy means an alloy whose molecular structure is at least 50 percent, and preferably at least 80 percent amorphous.
Another method and apparatus for producing a metal strip are disclosed in German Pat. No. 2,746,238 where various nozzle shapes, which are complicated to manufacture, are used for the production of "wide" metal strips. The greatest strip width obtainable is 12 mm. Within the system a plurality of parallel, uniform nozzle jets must strike a moving substrate from a suitable distance, e.g., to obtain relatively wide strips. However, testing of this system has led to difficulties, particularly since the nozzle jets do not combine to form a pool and it is very difficult to obtain strips with a uniform cross-section. It is also difficult, if not impossible, to obtain a pool with an adequately uniform thickness for drawing strips wider than about 7.5 mm with an approximately uniform cross-section.
To overcome these difficulties, German Pat. No. 2,746,238 proposes devices with stepped nozzle shapes located very close to the cooler surface. The system permits production of strips with more uniform thickness, widths, and uniform strength characteristics, up to the range of the aforementioned widths.
In conjunction with an apparatus for producing metal strips at a high speed, a nozzle body with a curved surface and a slot-like nozzle opening is known for influencing the flow conditions between the nozzle body and the cooler surface (e.g., European Pat. No. 0,040,069). The strips produced in this way mainly have an amorphous structure. Although coating of the cooler surface with different materials is described, it is used exclusively to obtain specific physical surface properties, particularly completely satisfactory and easy detachment of the produced strips from the cooler surface.
Finally, British Pat. No. 2,083,455 discloses a drum-like cooler with a circumferential slot. The circumferential slot on the drum, to a certain extent, serves as a mold for a relatively thick metal strip which can be subsequently cut at right angles to form small disks, as are conventionally used in the manufacture of semiconductors.
The conventional methods and apparatus for producing strips of the aforementioned type suffer from an important disadvantage in that they cannot, in a practical manner, produce strips significantly wider than about 15 cm, despite a very considerable need for such strips. Heretofore, such strips could only be produced by complicated and cost-intensive rolling processes. Wider strips with an amorphous structure are needed, e.g., for the production of transformers. Such transformers have approximately 30% lower magnetic reversal losses than conventional stacks of sheets.
Further, known methods and apparatus for producing strips of the aforementioned type are used exclusively for producing strips with homogeneous structures. Conventional methods or apparatus are not used for producing strips having juxtaposed areas with different metallurgical structures, or different geometrical structures. There is a considerable need for such strips, e.g. for packaging foils, which heretofore had to be produced by the more complicated and cost-intensive rolling process, and for mass-produced products, particularly small parts, from strip or foil material, which heretofore had to be stamped or punched out of closed foils or strips. The stamping or punching process is also complicated and costly.